(CNN) -- Thousands of tourists have been left stranded after two blasts at Bangkok's giant Suvarnabhumi Airport wounded four people and triggered its closure, dealing another blow to the country's travel industry.

The airport, which was swamped by protesters, is one of the major travel hubs in the region.

The blasts come a day after thousands of anti-government protesters stormed the airport in an ongoing battle to oust Thai Prime Minister Somchai Wongsawat, who was returning from an economic summit in Peru.

The travel industry has already seen a drop off in tourist numbers after protesters shutdown Phuket airport for two days in August and with continued anti-government protests in central Bangkok resulting in violence.

The British Foreign Office has warned tourists to take care in the city after two people were killed and more than 400 were injured during recent clashes between protesters and police. Watch more about the airport chaos »

Recent bomb and grenade attacks have resulted in an additional two deaths and 20 injuries.

The Foreign Office says "there remains a possibility of further violence," with the political situation in Thailand "very uncertain."

The U.S. State Department has also warned people traveling to Thailand to exercise caution, especially in locations where Westerners congregate.

"They should remain vigilant with regard to their personal security and avoid crowds and demonstrations."

Kongkrit Hiranyakit, head of the Tourism Council of Thailand, told The Associated Press that the bombings, at the height of the high season which runs from late October to February, could cut income from tourism to half the expected 240 billion baht ($6.8 billion). Watch what's behind protesters' demands »

The tourism industry is worth 6 percent of the economy and employs about a million people, with Suvarnabhumi handling 45 million passengers and three million tonnes of cargo per year.

Hiranyakit said when protesters closed Phuket airport tourist arrivals at it and nearby resorts plummeted by 17 percent. Fallout from the closure of Bangkok's main airport would likely be worse and could last six months or more.

"We don't know when it will recover," said Kongrit. "The government should be taking steps to solve this problem. Otherwise we cannot survive with this situation," he told AP. Watch fists fly in the terminal »

Association of British Travel Agents spokesman Sean Tipton told CNN there had been a slight drop off in the number of tourists traveling to Thailand but it did not believe the latest bombings would have too much of an impact.